Wiring & Cable Size Calculator (IS 732)
Compare cable cross-sections using load, distance and voltage drop. Results are planning estimates; final selection requires an installation-specific design.
| Size (sq mm) | Conduit Max Amps | Voltage Drop | Model comparison |
|---|---|---|---|
| 1 sq mm | 11 A | 4.83% | Outside model limits |
| 1.5 sq mm | 15 A | 3.23% | Outside model limits |
| Selected2.5 sq mm | 21 A | 1.98% | Within model limits |
| 4 sq mm | 28 A | 1.23% | Within model limits |
| 6 sq mm | 36 A | 0.82% | Within model limits |
| 10 sq mm | 50 A | 0.49% | Within model limits |
| 16 sq mm | 68 A | 0.31% | Within model limits |
| 25 sq mm | 89 A | 0.19% | Within model limits |
Cable size and household circuit questions
Which wire size is best for house wiring?
There is no single size for the whole house. Selection depends on current, route length, conductor material, installation conditions and protective devices. Assess lighting, sockets, appliances and distribution-board feeds for their own duties. This tool compares simplified calculations; have the actual circuit design checked before installation.
What does an actual cable-calculator example show?
With 3,000 W, a 20-metre one-way run, copper, 230 V single phase and the tool’s 3% voltage-drop setting, the calculator displays 15.35 A at an assumed 0.85 power factor, selects 2.5 sq mm, and gives 4.55 V (1.98%) voltage drop. These are model outputs, not approval for an actual circuit. A different power factor changes the current calculation.
What size cable is used for sockets and lights? Can I use 2.5 sq mm for sockets?
Do not choose a conductor from the outlet label alone. Check the load, circuit arrangement, installation method, route and protection. The worked example does not establish a universal socket or lighting cable size.
How much current can 1.5 sq mm wire carry?
A single figure without installation conditions can mislead. Cable construction, temperature, grouping and installation method affect current capacity. Use relevant manufacturer data and design requirements rather than treating a simplified table as universal.
Can a 1.5-ton AC run on 2.5 sq mm cable? Can AC run on 1 mm cable?
Cooling tonnage does not establish electrical current. Check the specific unit’s nameplate and installation instructions, circuit length, installation conditions and protective-device requirements. Do not approve either size from tonnage alone. The same checks apply to a proposed 1.5 sq mm AC or geyser circuit.
How many AC units can run on 10 sq mm cable?
Cable size alone cannot answer this. Establish the actual appliance loads, simultaneous operation, supply arrangement, installation conditions and protection. Also establish whether this is a shared feeder or separate appliance circuits.
What size wire is needed from the meter to a 100 A panel?
This needs a service-feed design. Confirm supply phase, permitted service capacity, conductor specification, route, voltage drop and protection with the electrician and electricity provider where applicable. The panel label alone cannot establish the cable size.
Does a low voltage drop mean the wire is safe?
No. Current capacity, fault protection, earthing, insulation and installation conditions must also be suitable. The 3% and 5% settings are comparison inputs, not a complete standards-compliance check. A qualified professional must establish the requirements for the actual installation.
Why can aluminium need a larger cross-section than copper?
Aluminium and copper have different electrical and mechanical properties. Compare the specified cables under the actual design conditions; do not assume that moving up one standard size always makes them interchangeable.
Related calculators
Continue with another electricity or backup-planning tool.
Reference official efficiency and safety guidance from Bureau of Energy Efficiency and standards information from Bureau of Indian Standards.
Calculation Assumptions & Safety
Calculations are planning estimates using the displayed inputs and assumptions, not certified designs or verified provider bills. Actual runtime, generation, cost and wire requirements vary with equipment, installation and operating conditions. Confirm manufacturer specifications and current provider rules. Have a qualified electrician review wiring and backup installations.
Keep installation costs separate from electricity bill benefits
Wiring and cable planning concern installation work. A recurring household bill subsidy does not automatically pay for that work or approve a cable size. Check the state-wise household electricity benefits guide when planning ongoing costs.
For your location, review PSPCL domestic subsidy conditions in Punjab, MP Atal Graha Jyoti bill relief or Delhi domestic subsidy eligibility. Eligibility and installation estimates are separate decisions.